Historically, when a caller telephoned a party, if the party to which the caller wished to speak with did not answer the phone or if the line was busy, the caller had to hang up and redial at a later time hoping that the second call would reach the intended party. Often times, the caller would need to attempt to contact the party multiple times in order to reach that party. If the caller had urgent information in which time was of the essence, this method was unsatisfactory and often resulted in the intended party missing important business or other opportunities.
Some of these problems were alleviated with the introduction of answering machines and voice mail systems. However, even these solutions were not completely satisfactory. For instance, utilizing answering machines and voice mail systems required the called party to actively retrieve their messages. Thus, either many important messages were still not received in a timely manner if the called party did not retrieve their messages frequently or the called party was required to check their voice mail or answering machine quite frequently when the party was out of the office or home in order to insure that messages were retrieved quickly. Thus, this results in the same problem as having the caller repeatedly call the intended party, except that in this case it is the called party that must waste its time insuring that no messages are missed.
A more recent solution to this problem is the introduction of subscriber's static reach list. A static reach list enabled a subscriber (i.e., called party) to enter a list of telephone numbers (or IP addresses, etc.) where the subscriber might be reached. The subscriber would enter these numbers in the order of preference in which the subscriber wished the telecommunications system to try to reach the subscriber. Therefore, if the subscriber were going to be away from the location of the subscriber's normal telephone number, if a call were received for the subscriber, the telecommunications system would redirect the subscriber's calls to the next number on the static reach list until the subscriber were reached or until the list of numbers was exhausted.
However, this method required the subscriber to know in advance the telephone number or other communications address at which the subscriber would be while traveling. Many times such information is unknowable either because the person does not know a number at the location to which they are travelling or because the person does not know sufficiently in advance where they will be in order to update the static reach list with the appropriate number. Therefore, it would be beneficial to have a method of to prevent a called party from missing calls without being required to know the number of a phone at which they will be in advance.